Cardiogenic Shock - Diagnosis and Treatment

Chapter 4 / Shock and ACS with ST Elevation 51
favoring patients who survived the initial phase of shock to be enrolled in a randomized
trial; the results of revascularization in clinical practice may not be as good as those
achieved in such trials (29). The results achieved with revascularization in the trials are
generally derived from hospitals experienced in the rapid performance of revascular-
ization in critically ill patients. For example, in the SHOCK trial, the median time from
randomization to revascularization was 0.9 h for patients undergoing angioplasty and
2.7 h for patients undergoing surgery (30). Such prompt institution of revascularization
treatment may not be able to be duplicated at many hospitals. Also, the success of
angioplasty performed by less experienced operators may be significantly lower than
that of the randomized trials, resulting in worse outcomes.
Nonetheless, the data are convincing that rapid revascularization reduces mortality
in patients with acute myocardial infarction complicated by cardiogenic shock.
Future Trends
The outcome of cardiogenic shock complicating acute coronary syndromes may be
improving. Goldberg et al. (32) demonstrated that the outcome of patients with cardio-
genic shock complicating acute myocardial infarction (Q-wave and non-Q-wave)
improved during a 23-yr period, with the greatest improvement in the last decade
(1990s): There was greater than a 70% in-hospital mortality among patients with car-
diogenic shock from 1975 through 1990, declining to 61% between 1993 and 1995 and
to 59% in 1997. This trend was evident despite the fact that patients with shock were
older and sicker in recent years. Similarly, the outcome of patients with myocardial
infarction and shock has improved over time in Israel, with 30-d mortality rates of 87%
in 1992, 84% in 1994, and 73% in 1996 (p = 0.02 for trend) (Jonathan Leor, written
communication, 1999). Although such observations can be influenced by changing dif-
ferent diagnostic criteria or surveillance for patients with shock, these reports, along
with the increasingly frequent performance of revascularization and results of random-
ized trials, suggest that current therapeutic approaches to shock are more effective than
prior approaches.
Algorithms of Outcome
Clinicians must frequently make difficult decisions concerning aggressiveness of
care of patients with cardiogenic shock complicating acute coronary syndromes. These
decisions are often made in the face of substantial uncertainty regarding the prognosis
of the individual patient. Because mortality in these patients is high and large amounts
of resources can be expended in a potentially futile effort, clinicians may consider not
offering aggressive measures to high-risk patients or withdrawal of aggressive mea-
sures in others. Recent results of trials, however, suggest that aggressive and highly
expensive care is often worthwhile. In order to help identify patients who might derive
particular benefit from such therapies, an algorithm was derived from the GUSTO-I
database (33) that allows clinicians to make more accurate estimates of the probability
of survival for patients with shock complicating ST-segment-elevation myocardial
infarction (Table 3). Similar to algorithms predicting the occurrence of cardiogenic
shock, this algorithm reveals that the likelihood of survival is heavily influenced by the
patient’s age and physical findings at the time of diagnosis. These data may help clini-
cians understand the likelihood of survival if aggressive measures are instituted to
patients with shock.
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